1. Technical Field
The present invention relates to a liquid ejecting head having a piezoelectric element having a piezoelectric layer containing a piezoelectric material and an electrode, in which liquid droplets are discharged from a nozzle opening, a liquid ejecting apparatus, and a piezoelectric element.
2. Related Art
Mentioned as the piezoelectric element is a piezoelectric material which exhibits a mechanoelectric conversion function, e.g., one in which a piezoelectric layer (piezoelectric film) containing a crystallized dielectric material is sandwiched between two electrodes. Such a piezoelectric element is carried in a liquid ejecting head, for example, as an actuator apparatus of a bending vibration mode. Mentioned as a typical example of the liquid ejecting head is, for example, an ink jet recording head in which a part of pressure generating chambers communicating with nozzle openings for discharging ink droplets is constituted by a diaphragm, and the diaphragm is transformed by the piezoelectric element to pressurize ink in the pressure generating chambers to discharge the ink from the nozzle opening in the form of ink droplets. Mentioned as a piezoelectric element carried in such an ink jet recording head is, for example, one in which a uniform piezoelectric material layer is formed by a film forming technique over the entire surface of the diaphragm, and the piezoelectric material layer is cut into a shape corresponding to the pressure generating chambers by a lithographic method to thereby form the piezoelectric elements in such a manner as to be separated for each pressure generating chamber.
The piezoelectric material to be used as the piezoelectric layer constituting such a piezoelectric element is required to have high piezoelectric properties. Mentioned as a typical example of the piezoelectric material is lead zirconate titanate (PZT) (JP-A-2001-223404). However, from the viewpoint of environmental problems, a non-lead piezoelectric material or a piezoelectric material in which the lead content is reduced has been demanded. Mentioned as piezoelectric materials not containing lead are, for example, a BiFeO3 piezoelectric material containing Bi, Fe, Ba, and Ti (e.g., JP-A-2007-287745).
When such a piezoelectric material containing Bi, Fe, Ba, and Ti is formed into a piezoelectric layer, there is a problem in that cracks are easily formed. When the piezoelectric layer has a portion directly disposed on the electrode (portion on a piezoelectric layer electrode) and a portion directly disposed on a member other than the electrode (portion other than a piezoelectric layer electrode), cracks are easily formed particularly in the portion other than the piezoelectric layer electrode. It is a matter of course that such a problem is not limited to the ink jet recording head and similarly arises in other liquid ejecting heads for discharging droplets of liquid other than ink and also in piezoelectric elements for use in members other than liquid ejecting heads.